Nowadays, the OIS technology of digital cameras and lenses has already been mature and popular, and the users have already fully understood the advantages of the OIS technology. When taking photos in some specific situations, such as in a low-light environment, the shake of hands affects the photo qualities very significantly, and may cause photos to be blurry. The OIS technology can effectively reduce the influence of the shake on the photos.
With the more and more extensive applications of miniature camera modules in mobile phones, the resolutions of the modules become higher and higher; in some specific situations, the shake of hands affects the photo qualities very significantly too. Although the users can solve the problem by increasing the light sensitivity, the area of the photosensitive element of each miniature camera module is highly limited; therefore, when a miniature camera module takes photos under a high light sensitivity, there will be much image noise, and the quality of the photos can be adversely affected.
Therefore, the industry has already actively researched and manufactured various OIS technologies for miniature camera modules. Some OIS technologies (for example, US Published Patent Application 20090237517 and CN Patent 200810090504.1) do not need accurate and reliable lens position sensors, and thus the volumes, complexities, and power consumption of camera modules can be reduced.
However, in the mass production of OIS motors, the characteristics of each OIS motor may be slightly different from the design characteristics due to the effect of errors generated in production, which may cause deviations of the relationship between control parameters and compensation angles. Therefore, in order to enable a camera module to achieve the best OIS effect in the absence of an accurate and reliable lens position sensor, each camera module requires tuning so as to find the relationship between its control parameters and its compensation angles. Wherein, the values of the compensation angles are equal to the values of the vibration angles, but the direction of the compensation angles are opposite to the directions of the vibration angles.
Since there is no widely used automatic tuning method at present, in the prior art, an OIS camera module may need to be manually tuned so as to find the relationship between the compensation angles of its angular vibrations and its control parameters. Since the relationship between the compensation angles and the control parameters varies with the focusing distance and the lens stroke, the relationship should be determined at several different focusing distances, and the objective needs to be placed at different distances. Therefore, the required time will be very long if the whole tuning process is manually performed by manpower. In mass production, too much manpower resource may be required, and the operating cost may be too high.
Furthermore, since existing tuning technologies require manual operations, their accuracies are limited by the skill of the operators. Therefore, it is very important to train and manage the operators, and the training and managing work may further increase the operating cost. Since each operator needs a set of tuning appliance and adequate space, and the existing technologies require many operators, these technologies require much setup cost, which comprises the cost of having large working space and the cost of arranging many appliances. Since the existing technologies require many operators, when the producing output needs to increase, recruiting the workers and increasing the area of the factory may take a long time, which limits the speed of increasing the output. Additionally, the reliability of tuning is also limited by the skill of the operators. Since the operators may be required to highly concentrate on the tuning process, it is very difficult to request an operator to keep high consistency, accuracy, and reliability for a long time.